2008 Corolla CE - Daily Driver Revival

Update: Starting and running real strong this morning!

Gonna run a bottle of cataclean today. Then I’ll find time to plug in the Carista to check out readiness monitors, 02 voltages, and probably fuel trims as well. If emissions systems are operational that'll be a very good sign the root causes of the mystery P0420 are solved.

At this point I'm skeptical if it even needed a new Catalytic converter a year ago, or it was just a lazy fix by my father. Poor ignition sending unburnt fuel through the original cat could have poisoned the cat or fooled the computer into thinking it wasn't working. A small exhaust leak in-between the upstream and downstream 02 sensors could have triggered it as well...

I'll be diagnosing this thing the right way instead of throwing a money at it. It'll only get a new cat if I confirm there are no exhaust leaks and the 02 sensors are mirroring (showing the cat is not scrubbing the exhaust as intended)... The code being stored with no CEL on for 500 miles was already a good sign. I'll see it through.

More important than emission codes it's running really good! So I'll celebrate that until I get some more data via Carista

 

When are you installing raptor lights on your old Rolla to spice things up?

(I will show myself out)

 

Hahahah I don't want to tempt the electrical gremlins.

When I started the car yesterday I was selecting music to play the door locks went crazy and actuated back and forth about five times. I thought "alright... It's haunted..."
Don't wake up the gremlins lol

 

Oh man, thread is going have me doing all the over due maintenance on the 2008 Yaris.

 

Start by checking ground.

One time, after I had to take dash apart on a car to get new evaporator and as I was connecting it all back got a few wrong. Turn signal activated horn, etc.... Took some time to figure it out. Now with smartphones just take pictures or video. Easy peasy.

 

Alright did some more digging with Carista.

p0420 still stored


Only one system not ready. Just the evap system (which can take quite a while for the computer to finish testing)


Judging by temp, the Catalytic Converter is working. I’ll have to poke around a little more to see live 02 voltage

at idle




Battery voltage is a bit low. Not surprising since the battery is 4 years old. 11.9v without the engine on. Alternator is barely keeping it alive. This might explain some of the odd electrical behavior at idle (common in early 2000’s Yotas)

and finally the big clue I was looking for:



Huge long term fuel trim adjustment. I’d expect +/- 10%… but this big of a correction is indicative of a vacuum leak or exhaust leak in between the AFR sensor(upstream) and 02 sensor(downstream)


I’ve inspected for vacuum leaks extensively at this point. But I haven’t had a chance to inspect for exhaust leaks… My money is on an exhaust leak on the flex joint or the infamous “donut” these things like to leak from. Both super simple fixes.

Good to know as it stands it will pass a Texas emissions test. Tx allows one system not ready. And they’ll look past pending (inactive) codes.

Still, it’s worth addressing the suspected exhaust leak eventually. For now, I’ll shift gears and swap the battery and get some fresh tires. The current tires are dated 2015! Carrie deserves fresh shoes. May even get some new hub caps and repaint the steelies!

 

2015? Yikes! My 4runner had 2016s when I bought it and we barely made it home on back roads, had 2 flats the next morning. What tires are you going with?

 

Bfg advantage control. 195/65/15.

Costco has them for $130/ tire with free installation. I’ll have them install new tpms sensors too since I’m tired of that light on the dash! lol

 

It's good that small exhaust leaks make themselves known by the black carbon marks they leave. Misfiring allows more unburned fuel to go out the pipe which could skew things. Maybe some driving around with the tuned-up ignition will lower the long-term fuel trim on its own? The plugs looked pretty good AFR-wise.

 

Hard to read the plugs with all that oil contamination. But you’re right an exhaust leak should be an easy find.

Luckily it’s running great now so I can focus on the more critical safety items like tires and a good battery.

This weekend I plan on working on the 4R a bit. If I have some time I’ll look into this potential exhaust leak. It could also be a valve stuck open in the evap system… this would sort of act like a perpetual vacuum leak. Clue for that is the evap system is not “ready” … I’ll just pop the evap line off and see if there’s vacuum there. Easy test

Two solid avenues I have to chase down the last 10% of efficiency and engine reliability…. But honestly right now it’s running fantastic

 

This is your very best friend when chasing exhaust leaks.

 

My best friend for chasing exhaust leaks is my nose and my eyes!

 

Try getting your nose or eyes up to the exhaust manifold on a Porsche!

 

Thank god I'm not a Porsche owner. Expensive crap! And I can't go offroad - well, I could, but I don't think a 4" lift and 35s would look that good on a 911!

 

I almost bought a 08 Cheyenne....
I'm glad I ended up with the 4runner.

 

I'd be scared to touch anything on that finely over-engineered German engine!

 

We've got a 08 Mercedes, rather fun to drive if you quit thinking about tire life!

Not our house or car just a internet picture.

 

That does look really nice! But anyways, we better keep this back on topic before we get kicked out of this thread!

 

Fine. @1SilverRunner nice Corolla! Our aunt in New Mexico drove one until they decided it wasn't worth putting more money into and then kept driving it until they were getting in and out of the passenger window and then totaled it in the desert doing donuts!

 

Despite the oil everywhere, the tan colour on the spark plug insulators looks good (IMO).

 

To me, that tan color indicates a lean condition. Especially considering the spark plugs were only 20k miles old and the ECU is making massive fuel trim corrections. 20 percent indicates a problem for sure. 25 percent will often trigger a check engine light. The computer on board knows something's up at that point.



*not my image.

Honestly with it running better than ever the only reason I'll keep hunting for that last bit of efficiency and reliability is the nerdy side of me thinking "it can do better"

My wife drove it when I got it back from my father and said "oh no what happened to it"
She drove it again recently and said it feels like it's back to normal.

I guess I just want "back to normal" to last another few years. At 20% trim something is definitely up. That ain't right.

 

Barring a exhaust leak you probably need injectors. Anything higher than 15% needs addressing. I had one car that was running 25% and new injectors didn't fix it no exhaust leak no nothing. Cleaned the MAF and checked the 02 sensors and everything checked fine and then the customer said they were tired of waiting and said fire the parts cannon. New MAF, new 02 sensors, and cleaned the throttle body. Not sure what fixed it but I went down to 5%.

 

There's a lot of clues I haven't really delved into with this thing.

One big clue is after clearing fuel trims LTFT almost immediately returned to 20%. Which indicates whatever is happening is constant.
Certainly could be a fuel filter, fuel pump or injectors.
It could also be a vucuum leak (external or internal via the evap system)
It could also be an exhaust leak at the exhaust gasket or anywhere up stream of the 02 sensor.
It could also be the MAF overcorrecting
It could be a lazy downstream 02 sensor

The difference between me and many folks is I'm not going to throw money at this thing when it may not need it. I'll confirm what parts it needs first. My goal is to save money and save the 4Runner. I'm certainly not saving any money if I go out and buy a new fuel pump assembly, injectors, MAF, AFR sensor, 02 sensor, CAT, exhaust manifold, downpipe. That's what bad techs do and they waste a lot of money doing it... It likely needs one of these things. The trick is finding which one.


One thing I'm dying to do is to hold the engine at 2,500 rpm and watch LTFT. If trims stay high (+20%) it's likely an exhaust leak or fuel delivery issue (filter, pump, or injectors)

Vacuum leaks typically improve at higher RPM so this little test is something I'll certainly do this weekend. My money really is on exhaust leak. To many variables with an aftermarket CAT installed by a mystery shop that only lasted 6 months before p0420 came back on. (Very likely the CAT was never the problem)

Another thing I'll do is disco the purge valve while the engine is idling, pull the vacuum hose off the valve and check for vacuum suction at that port. If that valve is stuck open that's my vacuum leak. Doesn't look like a traditional vacuum hose leak.

There's a lot of little clues and correlations between codes, symptoms, common faults and leaks. It's actually difficult to type it all up. But rest assured I'll run some test and fix the issue. Ideally without throwing money at it. Keep in mind I'm also not in a huge rush to find it. It already drives 10x better than it was.

Right now, I'm really happy it's driving so well! Getting it's new rubber and battery today!

 

Ah the old spark plug debate.

it’s like, reading tea leaves, but for gear heads

 

Great car, but a weak spot is hydraulic ABC suspension. Make sure to change your fluid before the pump granades and takes out all valve bodies.

 

Things I never even know about. It's new to us from a guy who decided he may as well give it to us instead of the dealer.

 

Looking online it just has standard coil/strut suspension.

 

Is that not pre-facelift R230 Mercedes SL? If yes, then in US they were sold only as SL 500 with V8 and ABC.